The world rejoiced as peterandsarah@blueyonder.co.uk (Peter and Sarah Childs) wrote:
> However there is a third way. That should be safe but some
> people may disagree with me! If you can "freeze" the disk while you
> take the backup. The backup can be used as if the computer had
> crashed with no hard disk failure at all. Ie WAL will be consistant
> and database may take longer but once it is up it will be safe (like
> paragaph 1). Now freezeing a disk for backup is not that
> difficult. You should be doing it anyway for user file
> consistancy. (You don't want the first 30 pages of you document to
> disagree with the end because somone was saving it during the
> backup!
I heard D'Arcy Cain indicate that some SAN systems (I think he
mentioned NetApp) support this sort of thing, too. Digital's AdvFS
also supports it.
Of course, if you take this approach, you have to make _certain_ that
when you "freeze" a replica of a filesystem, that _ALL_ of the
database is contained in that one filesystem. If you move WAL to a
different filesystem, bets would be off again...
--
let name="cbbrowne" and tld="ntlug.org" in String.concat "@" [name;tld];;
http://www3.sympatico.ca/cbbrowne/
The real problem with the the year 2000 is that there are too many
zero bits and that adversely affects the global bit density.
-- Boyd Roberts <boyd@france3.fr>